1. Field of the Invention
The present application relates to an over-current protection device, and more particularly to an anti-surge over-current protection device.
2. Description of Related Art Including Information Disclosed under 37 CFR 1.97 and 37 CFR 1.98
Anti-surge protection can detect over-voltage event and instantly stop surge voltage, and at the same time cut off the over-voltage power source to protect a relevant system. The protection may be triggered to turn of the power spontaneously if a fluctuation of the power transiently differentiates from a standard value by 10% or more.
In USB applications, surge current may occur due to transient low resistance when hot plugging, and therefore voltage may fluctuate violently. In such circumstance, a traditional positive temperature coefficient (PTC) device may trip to provide over-current protection. However, the PTC device usually responds in several milliseconds and the anti-surge protection apparatus, normally a semiconductor device, can quickly responds in several nanoseconds; therefore the anti-surge protection apparatus would turn off or restart the system before the PTC device activates. Nevertheless, such surge phenomenon is not harmful to electronic devices, and the PTC device is able to protect the electronic devices even if damage to the electronic devices occurs. The unexpected turn-off and restart of the system may incur data loss and inconvenience of waiting for restarting. Although the anti-surge semiconductor device can redesign to overcome this problem, it is costly especially for an apparatus of several USB ports in view of much expensive semiconductor processes.